Heating unit



April 23, 1963 l.. c. HANSON 3,087,042

HEATING UNIT Filed Feb. 29. 1960 6 Sheets-Sheet 1 April 23, 1963 c. HANsoN 3,087,042

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HEATING UNIT Filed Feb. 29. 1960 6 Sheets-Sheet 4 April 23, 1963 L. c. HANSON 3,087,042

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L. C. HANSON HEATING UNIT April 23, 1963 eg) m j l l y H I Ofgy C Filed Feb. 29. 1960 United States Patent Othce 3,087,042 Patented Apr. 23, 1963 3,087,042 HEATING UNIT Leroy C. Hanson, Elmhurst, Ill., assigner to Ferro Corporation, a corporation of Ohio Filed Feb. 29, 1960, Ser. No. 11,824 16 Claims. (Cl. 219-37) rllhis invention relates to an electric heating unit for a stove or countertop cooking assembly.

An electric heating unit for cooking and the like may comprise a coiled he-ating element mounted on a multiarm support or spider which rests on shoulders in a ring or pan carried in an opening in a cooking surface. 'Ihe heating element has terminal end portions which `are connected with a source of electrical power, through suitable manual or automatic control circuitry.

It is a principal object of this invention to provide an improved terminal block and guide assembly construction for the terminal end portions of the element which permit ready removal of the element from its support for cleaning, repair or replacement.

One feature of the invention is the provision of a heating unit of an element having terminal end portions with a terminal block mounted on and joining the end portions, a support -for the element and guide means associated with the support receiving and guiding the terminal block upon insertion and removal of the element in the support; and more speciiically the guide means lare associated with a `depending wall portion of the supporting structure which has an opening therein through which the terminal block is moved.

Another feature of the invention is the provision of a second terminal block which carries circuit means for connection with the terminal end portions of the heating element and the guide means direct the first terminal block into a position with the terminal end portions in contact with such circuit means.

A `further feature is that the guide means comprise channel members having U-shaped conguration mounted in opposed relation, one on either side of the opening in the depending Wall, the legs of the U being spaced apart farther than the thickness of the first terminal block, permitting manipulation of the terminal block as it moves through the guide. Yet another feature is that the lower channel supporting surface Ahas a portion adjacent the depending wall which is inclined.

Still a further feature is that the terminal blocks have slots `formed therein beneath and aligned with each of the element terminal end portions, preventing the accumulation of dirt.

And another feature is that the terminal end portions of the heating element have grease guards mounted thereon adjacent the terminal block; `and the grease guards on the outermost of the terminals are plates which have portions embracing the ends of the terminal blocks and releasably secured thereto. Spring contacts on the channel guide members engage the plate portions providing a ground connection `for the she-aths of the elements.

A yfurther -feature is the provision in a stove of two electrical heating units each having plug-in elements, receptacle and support for each element, and means associated with at least one of the receptacles and elements for blocking entry of an element into the incorrect receptacle. This is particularly important in a stove having one or more units with a thermostatic sensing device to insure that the sensing element is not connected inadvertently across a power circuit.

Still another feature is the provision of various arrangements :or mounting the second or iixed terminal block either on the depending wall of the unit support or beneath the cooking surface. The terminal fblock may 2 be mounted for adjustment toward and away from the opening in the depending support wall to insure the proper relationship of the circuit means and element terminals.

Yet another yfeature is the provision of a heating unit of relatively shallow dimension with the guide larrangement for the element terminal block extending straight from the wall of the support and at a slight downward angle. Preferably the walls of the guide are ared permitting manipulation of the terminal block during insertion `and removal.

Another feature is the provision of a terminal block guide structure associated with the opening in the wall of the supporting ring yfor a heating element in which circuit connections are made ydirectly tothe terminal block mounted on the ends of the terminal portions of the elements Ias through wires, and in which the edges of the terminal block guide structure are rounded to avoid damage to the electrical wires.

Further features and advantages of the invention will readily be apparent from the following specicaion and from the drawings, in which:

FIGURE 1 is a .plan view of a heating unit embodying the invention;

FIGURE 2 is an enlarged fragmentary perspective of the terminal block and guide arrangement with the heating element partially removed;

FIGURE 3 is a pl-an view of the heating element terminal block;

FIGURE 4 is an end view of the heating element terminal block taken generally along line 4-4 of FIG- URE 3;

FIGURE 5 is a vertical section through the element terminal block taken generally along line 5-5 of FIG- URE 3;

FIGURE 6 is a top plan of the two terminal -blocks fully engaged;

FIGURE 7 is a bottom plan of the two terminal blocks fully engaged;

FIGURE 8 is a fragmentary horizontal section taken lgenerally along line 8-8 of FIGURE 9;

FIGURE 9 is an enlarged fragmentary elevation of the heating element terminal block;

FIGURE yl() is a side elevation of the terminal blocks and guide structure, with the terminal blocks partially separated;

FIGURE l1 is a plan view of a modified heating unit;

FIGURE 12 is an enlarged fragmentary exploded plan view of the terminal block arrangement of FIGURE l1;

FIGURE 13 is a section taken generally along line 13--13 of FIGURE 12;

FIGURE 14 is a view similar to FIGURE 13 with the heating element terminal block lfully inserted;

FIGURE 15 is a vertical section taken generally along line 15-15 of FIGURE 12;

FIGURE `16 is a fragmentary plan view of a modified interlock arrangement;

FIGURE 17 is a fragmentary top plan view of a modied terminal block mounting arrangement;

FIGURE 18 is a fragmentary bottom plan view of the mounting arrangement of FIGURE 17;

FIGURE 19 is an end elevation of the mounting arrangement of FIGURE 17 taken generally along line 19-19 of FIGURE 17;

FIGURE 20 is a top plan view of a Ifurther modcation of the heating unit;

FIGURE Z1 is a fragmentary vertical section taken generally `along line 21-21 of FIGURE 20;

FIGURE 22 is a fragmentary vertical section taken generally `along line 22-22 of FIGURE 20;

FIGURE 23 is a broken elevation of a modification of the unit of FIGURE 20;

FIGURE 24 is a fragmentary perspective of the terminal block of FIGURE 23;

FIGURE 25 is an elevation of a unit incorporating a modified terminal block; and

FIGURE 26 is a fragmentary top plan view of the terminal `block of FIGURE 25.

Electrical surface heating units lare widely used in ranges or stoves and in built-in cooking assemblies. In general, most of the heating units have a flat coiled heating element `containing an electrical resistance supported in a metallic sheath by ian electrical insulating material. The coiled element is mounted on a supporting framework or spider received in a ring set in or formed in a surface of `the stove or built-in unit. The terminal end portions of :the heating element extend through a wall in the supporting rin-g, or in `a drip pan carried by it, and are connected with electrical conductors through which the element is energized. Many such units incorporate a hinge arrangement about which the element and its support may be pivoted upwardly to permit cleaning. This pivotal mounting requires substantial space beneath the cooking surface to accommodate movement of the terminal end portions of the element, the connecting conductors, and in many cases a terminal Iblock structure. A novel construction is disclosed herein providing a terminal or terminal block guide and support which allows manipulation and removal or replacement of the heating element within ya minimum of space.

Turning now to the drawings and particularly to FIG- URES l-lO, a heating unit '35 is illustrated received in an opening 36 formed in a cooking surface 37. A removable ring 38 has an outwardly extending curved ange 39 which rests on the top of the cooking surface 37 and a depending wall 4t) which terminates below the cooking surface in an inwardly directed lip 41. A removable drip pan 44 has an outwardly directed flange 45 at its upper edge which rests on lip 4I.

Two heating elements 46 and 47 have an interlaced fiat spiral configuration and are mounted on the arms of a su porting structure or spider 48 received within the circular opening defined by wall 40 land resting on the flange 45 of the drip pan 44. Each of the heating elements 46 and 47 have a pair of terminal end portions, 46a, 46b and 47a, 47b, respectively, which extend downwardly and outwardly from the element proper through an opening 50 in the depending wall 44a of the drip pan.

Tlhe terminal end portions of the elements are generally 'aligned in a horizontal plane and -loosely joined together by a terminal fb'lock 52 of a suitable insulating and heat resistant material. 'Ihe outermost of fthe aligned terminal end por-tions, 46a and 46h, have secured thereto plates 53 and 54 provided with forward extensions 5S and 56 which embrace the ends of 4terminal block 52. Tabs 57 and 58 are struck inwardly from plate portions S and 56 4and engage shoulders 59 and 60 formed in the ends of the terminal block securing the block to the terminal end portions of the element.

As :best seen in FIGURE 8, the sheath 62 of the element terminates within terminal block 52 while a connector 63 yfor the heating element extends beyond the end thereof. Fixed `to the end of connector 63 is a male plugin contact 64 which extends outwardly on Ithe far side of the terminal block. The Iopening through the terminal block includes a iirst portion 65, generally circular in cross-section within which the end of sheath 62 is loosely received. A second portion 66 of the opening loosely receives `and generally conforms with the vconformation of the base of male `contact 64.

Plates 53 and 54 which secure the terminal block 52 on :the ends of the elements serve' also as guards blocking entry of grease or food particles `into the openings in the block. Collars 67 and 68 on terminal end portions 47a and 47b serve the same function. Slots 70 are formed in terminal yblock 52 extending inwardly from the surface adjacent the grease guards and downwardly from the termina-l end receiving holes 65 to permit food particles and the like to drop out of the block so that a deposit of food is not built up.

A xed terminal block '74, also of an electrical insulating and heat resistant materia-l, is carried yby a pair of bracket members '75 and 76 which have upward extensions 76a secured to` the outer surface of depending wall portion 46 of the unit supporting ring 38. Female receptacles or contacts 77 are provided in the body of block 74- to receive the male contact portions 64 attached to the terminal ends of the heating elements. Binding screws '78 on the upper surface of terminal `block 74 are provided for the attachment of conductors connected with an external source of power (not shown). Slots 79 are provided in terminal block 74 aligned with each of the female contact elements to reduce the problem of accumulation of food particles, as in terminal block S2.

The bracket structures '7S and 76 which support terminal block 74, serve as guides for the insertion and removal of terminal block 52. The brackets include a pair of U-shaped channel portions 81 `and 82, the legs of which open toward each other and which are roughly coincident with or extensions of the edges of opening 50 through which the element terminal block 52 is inserted and removed. Upon insertion of the heating element assembly the portion of the supporting spider 48 opposite terminal block 52 must be elevated to clear the top of the flange 39 of the supporting ring and accordingly the terminal block is tilted from its end position. The spacing between the guide channel legs, as 81a and Slb, is slightly greater than the thickness of block 52 to accommodate the necessary manipulation of terminal block 52. The lower leg 81h tof the guide channel, which serves as a supporting surface for terminal block 52, has two portions Slb' and SIb (FIGURE l0), with portion 81b" adjacent the element support land opening 50 inclined upwardly to receive and guide the terminal block during the initial portion of its insertion, and the nal portion tof its withdrawal.

When an element assembly is inserted `the male contacts 64 enter between the spring portions of the female contacts 77 in generally longitudinal direction (related to the axis of male contact 64) and with a wiping action. When the male contacts are fully seated axially and the element `supporting structure 48 clears the edge of the support ring flange 39 the outer portion fof the element Iassembly is lowered into the opening swinging male contacts 64 upwardly between female contacts 77, again with a wiping action. This dual, sequential wiping action aids in keeping the electrical contacts clean and maintaining a good low resistance electrical circuit.

Spring contact members 83 and 84 are formed in the side walls of the bracket and guide portions 81 and 82 and engage the portions 5S and 56 of plates 53 and 54. This contact completes a circuit with the sheaths 62 of the heating elements and may be connected with an external ground through a conductor secured to a binding screw 85.

Terminal block 52 may readily be detached from the terminal end portions of the heating element by disengaging latching tabs 57 and 58. Block 52 may then thoroughly be cleaned `as by scrubbing or the like and any food or dirt on the terminal end portions of the heating element may be removed.

A modied form of the invention is illustrated in FIG- URES ll-l5. The heating unit 89 includes a single heating element 90 having terminal end portions 91 and 92. The heating element 9@ is mounted on a spider support 93 which carries as its center a thermal-sensing device 94 having a pair of terminal end portions 95 and 96. The element 9i) and sensing device 94 are supported in a suitable ring lstructure 97.

A terminal block 98 loosely joins the terminal end portions 9'1-92 and 95--96 which are provided with male contact elements 99a and 99b, respectively. Fixed terminal block `100 is carried by brackets 101 and 102 mounted on the ring 97 and including suitable guide structures 103 and 104 which may be generally the same as those in FIG- URES 2, 6, 7 and 10. Terminal block 100 has four female contacts which receive Ithe male contacts as described above. Binding posts 106 and 107, which connect with the heating element are connected through conductors with .the power output terminals of a control circuit 109. Binding posts 110 and 111, which connect with the thermal-sensing device 94, are coupled with the control circuit, which is connected through conductors 112 with a suitable source of power as 110l volts A.C. The operation of the control system is not a part of this invention and it is suiicient to say that thermal-sensing device 94 is responsive to the temperature of the pan or other article being heated, turning the electrical power to the heating element `on and off to maintain a desired or preset temperature.

The thermal-sensing device 94, which may be a bimetal strip, would be damaged or destroyed if it were connected with a source of energizing potential (110-22.0 volts) such as used for the heating elements. As the construction yof the unit of FIGURE 11 is quite similar to that of FIGURE 1 and units of both types are commonly used in a single stove or built-in cooking assembly, it is desirable to provide some means for preventing the insertion of the heating element assembly including the thermal-sensing device in the receptacle -of FIGURE l where the device could accidentally be subjected to a high voltage. Accordingly, .the element terminal block 98 of the unit of FIGURE l1 is provided with a pair of upstanding ears 114. The guide channels 8,1 and 82 (FIGURES 2 and 6) have extension portions 115 on the upper legs thereof which project inwardly toward each other a suicient distance to bar the passage of ears 114, if the assembly of FIGURE 1l should inadvertently be inserted in the receptacle of FIGURE 1.

A modified interlock arrangement is illustrated in FIG- URE 16 where the element terminal block 118 of a two element unit is provided with a groove 119` in its upper surface which accommodates or mates with a downturned lip 120 formed in a plate 121 bridging the terminal block guides. Where this structure is used for a two element unit, the element terminal block of a single element thermal control unit has no such groove preventing its insertion in an incorrect receptacle.

In certain thermal control circuits 109 it is necessary that the connection between the binding screws 110 and 111 never be open-circuited, even though the element assembly itself is removed. A pair of ilexible contact strips 123 and 12.4 are connected with binding posts 110 and 111 and have portions lying along the rear face of terminal block 100. The end 123 of contact strip 123 overlies a portion of strip 124 shorting the terminals together. A pusher member 125 is carried in an opening 12.6 in the wall of terminal block 100 in a position to be engaged by one of the terminals 99b associated with the circuit of thermal sensing element 94. When the element assembly is received in ring 97, pusher member 125 forces contact portion 123 outwardly breaking the contact with connector 124. However, when the element assembly is removed the two connectors contact each other shorting the control circuit. It will be noted that the male terminals 99b are slightly longer than terminals 99a associated with the heating element. This extra length is necessary to open the short circuit and if a dual heating element assembly is inadvertently inserted in the receptacle of FIG- URE ll the circuit is not opened and control circuit 109 is not subjected to damage by having a high resistance connected across it.

A further modification of the invention is illustrated in FIGURES 17 and 19. The opening 130 in cooking surface 131 is provided with a depending flange 132 to which are secured brackets 133 and 134 which provide a terminal block guide structure and support terminal block 13S. The heating element assembly (not shown) which may be identical with that of FIGURES 1-10, is received in a separate ring 136 which is seated in opening 130 and which may be releasably held in place by spring clips (not shown). The ring 136 has a depending wall 137 with an inwardly extending flange 138 on which a removable drip pan 139 is carried, the drip pan being provided with an opening 140 through which the element terminal structure may be inserted or removed. With terminal block 135 supported directly from the cooking surface rather than from ring portion of the heating unit it becomes desirable to provide a degree of adjustment of position of the terminal block so that it may properly rece-ive the male contacts of a heating element assembly. The bracket assem-blies 133 and 134 are mirror images of each other and only one will be described in detail. A bracket member 142 is bolted to the cooking surface flange 132 and carries a channel support 143 having a slot 144 formed in the face thereof. The terminal block `support and guide `channel 145 has an extension 146 which is slidably received in channel support 143 and to which a binding -screw 147 is threaded. Channel 145 may be moved relative to supporting channel 143 to effect proper positioning of block 135 and screw 147 tightened to maintain the ldesired position. The ared inner edge 148 of guide channel 145 facilitates insertion of the element terminal block.

FIGURES 20-24 are concerned with two forms of plug-in surface units particularly designed for shallow mounting applications, i.e., mounting in a place where there is a minimum space between the supporting or cooking surface or an underlying surface or panel. This situation is most often encountered in built-in units which may be placed in the countertop above the kitchen cabinets or the like. In FIGURES 20-22 a unitary supporting ring and pan 152 is received in an opening 153 in cooking surface 154. Heating elements 155 are carried on spider 156 supported on shoulders 157 formed in the wall of the pan 152. The bottom 158 of pan 152 is spaced below the heating elements 155 by a distance only suicient to prevent excessive heating of the pan. An opening 160 is provided in the wall 152a of ring and pan 152, through which the terminal end portions 161 of heating elements 155 extend. Fixed terminal block 162 is carried by combined bracket and channel members 163 and 164 which are generally straight and extend slightly down- -wardlly from opening 160. The upper and lower walls '163e and 1631) of the guide are iiared to accommodate the necessary manipulation of terminal block 165 connected with the terminal end portions 161 of the heating elements during insertion and removal. This construction reduces the overall height of the entire unit permitting installation in a minimum vertical space.

A slightly different arrangement is illustrated in FIG- URES 23 and 24 where the cooking surface 170 has a raised ring portion 171 and depending wall 172 formed directly therein, as by a stamping operation. This type of construction is particularly suited to a single `or multiple element built-in range such `as a builder might install in a ktichen. The lower edge 173 of wall portion 172 is turned inwardly and supports a removable drip pan 174. The opening 175 for the element terminal -block is adjacent the upper edge of the wall portion 172, Ias close to the level of surface as practical. Again the supporting and guide brackets 176 and 177 incline downwardly and away from opening and carry terminal block 178 slightly below the surface 170. As in FIGURES 20-22 the upper and lower guide surfaces lare ared to permit manipulation of the element terminal `block during insertion and removal.

A loose trim ring 180 is placed over the formed ring 171, preferably of stainless steel. The central portion of ring 180 is spaced above the formed ring 171 providing a slight air space 181i which insulates surface of ring 171 preventing it from becoming excessively heated. The surface of 179 and 171 commonly has a finish as of porce-y lain or enamel which can be damaged by high temperature.

FIGURES 25 and 26 illustrate the adaptation of thev present invention to a unit in which the connecting wire conductors are permanently attached to the terminal block affixed to the terminal end portions of the heating element. A ring 185 with a depending wall portion 136- is seated in an opening in cooking surface 1%57 and has a removable shallow pan 188 in the bottom thereof. An opening 189 in wall 186 accommodates terminal block 19t) attached to the terminal end portions of cooking elements 191. Terminal block guide structure 192 includes a lower supporting surface 93, edge surfaces 194 and 195 and an upper surface 196. The central portion of the lower supporting surface is relieved at 197 to prevent unduly interfering with the leads 198 connected with the terminal block. All the edges of the guide structure, as at 290, 261, 202, 203 and 2M are curved to permit the conductors to slide over them easily upon 4removal and insertion of the heating element. The dimensions of the guide are such that terminal block 190 has sufficient freedom to permit the necessary manipulation of the element assembly upon removal and insertion.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention yas disclosed in the appended claims.

I claim:

l. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a lsupport for said element including a depending wall portion with an opening therein; and elongated guide means extending outwardly from and generally in alignment With said opening, receiving `and guiding said terminal block.

2. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; `a support for said element including a depending wall with an aperture therein; a second terminal block mounted in operative relation with `said support adjacent said aperture; circuit means for connection with said terminal end portions and carried by said second terminal block; and guide means extending between the aperture and the second terminal block receiving and guiding said first terminal block into `a position with said terminal end portions in engagement with said circuit means.

3. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element including a depending `wall portion with an opening therein; a second terminal block; circuit means for connection with said terminal end portions and carried by said second terminal block; and a combined bracket and guide structure carrying said second terminal block adjacent said opening and having guide surfaces receiving and guiding said first terminal block.

4. In a heating unit: a heating element having terminal end portions extending therefrom; a rst terminal block mounted on and joining said terminal end portions; a support for said element including a depending wall portion with an opening therein; a second terminal block; circuit means for connection with said terminal end portions and carried by said second terminal block; and a pair of channel members secured to said support and carrying said second terminal block spaced outwardly from and in alignment with said opening, said channel members receiving and guiding said first terminal block` 5. "Ille heating unit of claim 4, wherein said channel members have a U-shaped conliguration and are mounted in opposed relation one on either side of said opening, and the legs of the U members are spaced apart a distance greater than the thickness of said iirst terminal block.

6. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element including a depending wall portion with an opening therein; a second terminal block; circuit means for connection with said terminal end portions and carried by said second terminal block; and a pair of channel members secured to said support and carrying said second terminal block spaced outwardly from and in alignment with said opening, said channel members receiving and guiding said iirst terminal block, said channel members having a lower channel supporting surface `with the portion of said supporting surfaces adjacent said opening being inclined.

7. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element; a second terminal block mounted in operative relation with said support; circuit means for connection with said terminal end portions and carried by said second terminal blocks; male Contact elements on one of said terminal blocks; mating female contacts on the other of said terminal blocks; and guide means receiving and guiding said first terminal block, said guide means having a plurality of angularly related supporting surfaces for said first terminal block directing movement of said iirst terminal block to effect sequential wiping engagement between said male and female switch contacts in each of two directions.

8. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and loosely joining said terminal end portions; a support for said element; a second terminal block mounted in operative relation with said support; circuit means for connection with said terminal end portions and carried by said second terminal block; and guide means receiving and guiding said rst terminal block into a position with said terminal end portions in engagement with said second terminal block.

9. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions, said terminal block having slots formed therein beneath and aligned with each of said terminal end portions; a support for said element; a second terminal block mounted in operative relation with said support; circuit means for connection with said terminal end portions and carried by said second terminal block; and guide means receiving and guiding said first terminal block into a position with said terminal portions in engagement with said second terminal block.

l0. In a heating unit: a heating element having two coils with four terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; grease guards on at least one of said terminal end portion of each coil, secured with said terminal block; a support for said element; a second terminal block mounted in operative relation with said support; circuit means for connection with said terminal end portions and carried by said second terminal block; and guide means receiving and guiding said first terminal block into a position with said terminal end portions in engagement with said second terminal block.

ll. A heating unit of the character described in claim l0, wherein said terminal ends are aligned and plates are secured to the outermost terminal end portions, said plates having portions embracing the ends of the terminal block and spring means releasably secured therewith holding the yblock and terminal end portions together.

l2. In a heating unit: a cooking surface having an opening; a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element in said opening and including a depending wall portion with a second opening therein; a second terminal block; a multi-element bracket carried by and below said surface adjacent said second opening and supporting said second terminal block for movement toward and away from said second opening; circuit means for connection with said terminal end portions carried by said second terminal portion; and guide means receiving and guiding said rst terminal block into a position with said terminal end portions in engagement with said second terminal block.

13. In a shallow heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element having a wall with an opening therein; a second terminal block mounted in operative relation with said support outside said wall and below said opening; circuit means for connection -with said terminal end portions carried by said second terminal portion; and guide means extending downwardly at an angle from said opening, receiving and guiding said rst terminal block into a position with said terminal end portions in engagement with said circuit means.

14. In a shallow heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element having a depending wall forming a recess within which said element is received with an opening through said wall adjacent the top thereof; a second terminal block mounted in operative relation With said support adjacent said opening; circuit means for connection with said terminal end portions carried by said second terminal portion; and straight, flared guide means extending downwardly at an angle from said opening, receiving and guiding said 10 first terminal block into a position with said terminal end portions in engagement with said circuit means.

15. In a heating unit: a heating element having terminal end portions extending therefrom; a terminal block mounted on and joining said terminal end portions and having electrical conductors connected thereto; a support for said element including a depending wall portion with an opening therein; and guide means associated with said opening and extending downwardly at an angle therefrom, receiving and guiding said terminal block, said guide means being generally straight and flared outwardly with rounded edges.

16. In a heating unit: a heating element having aconductive sheath therearound with terminal end portions extending outwardly therefrom; a terminal block mounted on and joining said terminal end portions; a support for said element including a depending wall portion with an opening therein; guide means associated with said opening receiving and guiding said terminal block; and an electrical connector carried by said sheath and in engagement with said terminal block guide means forming a ground connection for said element, said electrical connector including a plate secured to said sheath with a spring contact member engaging said guide.

References Cited in the le of this patent UNITED STATES PATENTS 2,392,692 Price Jan. 8, 1946 2,502,988 Price Apr. 4, 1950 2,684,431 Cunningham July 20, 1954 l2,699,487 Turner Ian. 11, 1955 2,790,062 McOrlly Apr. 23, 1957 2,806,122 Thunander Sept. 10, 1957 2,877,334 McOrlly et al Mar. 10, 1959 2,938,989 Smith May 31, 1960 2,957,068 Hanson Oct. 18, 1960 3,002,079 Smith et a1. Sept. 26, 1961 3,017,491 Ammerman Jan, 16, 1962 

8. IN A HEATING UNIT: A HEATING ELEMENT HAVING TERMINAL END PORTIONS EXTENDING THEREFROM; A TERMINAL BLOCK MOUNTED ON AND LOOSELY JOINING SAID TERMINAL END PORTIONS; A SUPPORT FOR SAID ELEMENT; A SECOND TERMINAL BLOCK MOUNTED IN OPERATIVE RELATION WITH SAID SUPPORT; CIRCUIT MEANS FOR CONNECTION WITH SAID TERMINAL END PORTIONS AND CARRIED BY SAID SECOND TERMINAL BLOCK; AND GUIDE MEANS RECEIVING AND GUIDING SAID FIRST TERMINAL BLOCK INTO A POSITION WITH SAID TERMINAL END PORTIONS IN ENGAGEMENT WITH SAID SECOND TERMINAL BLOCK. 